Ultra‐broadband directional thermal emission

作者：Qiuyu Wang, Tianji Liu, Longnan Li, Chen Huang, Jiawei Wang, Meng Xiao, Yang Li, Wei Li · 发表于：Nanophotonics · 年份：2024 · DOI：10.1515/nanoph-2023-0742 · 被引用次数：26 · 研究领域：Thermal Radiation and Cooling Technologies、Optical properties and cooling technologies in crystalline materials、Thermal properties of materials

Directional control of thermal emission over its broad wavelength range is a fundamental challenge. Gradient epsilon-near-zero (ENZ) material supporting Berreman mode has been proposed as a promising approach. However, the bandwidth is still inherently limited due to the availability of ENZ materials covering a broad bandwidth and additional undesired omnidirectional modes in multilayer stacking with increased thickness. Here, we show that broadband directional thermal emission can be realized beyond the previously considered epsilon-near-zero and Berreman mode region. We then establish a universal approach based on effective medium theory to realizing ultra-broadband directional thermal emitter. We numerically demonstrate strong (emissivity >0.8) directional (80 ± 5°) thermal emission covering the entire thermal emission wavelength range (5-30 μm) by using only two materials. This approach offers a new capability for manipulating thermal emission with potential applications in high-efficiency information encryption, energy collection and utilization, thermal camouflaging, and infrared detection.